Improvement in piano-fortes



UNITED STATES SPENCER B. DRIGGS,

PATENT GEETQE.

OF NEWv YORK, N. Y.

IMPROVEMENT IN PIANO-FORTES.

Speciiieation forming part of Letters Patent No. 41,977, dated MarchQ72, 1864.

To all whom it may concern:

Be it known that I, SPENCER B. DRIGGS, of the city, county, and State ofNew York, have invented certain new and useful Improvements inPiano-Fortes and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccompanying drawings, iorming a part ot' this specification, in which-Figure l is a plan of the interior of a grand piano-forte constructedaccording to my invention. Fig. 2 is a horizontal section of the samebelow the sound-board. Fig. 3 is a longitudinal vertical section of thesame.

Similar letters of reference indicate corresponding parts in the severaliigures.

This invention consists in the employment of straight bridges throughoutthe whole scale of apiano-forte, whereby, besides allowing much morefreedom of vibration to the board, the strings are enabled to bearranged in overstrung tiers or sections through the middle of theboard, and I am enabled to obtain a more perfect scale as to theproportionate length ot' strings, and to obtain aprogressively-increasing distance between the notes on the bridgestoward the bass, which latter result is of great importance, for as thestrings of the lower notes require longer vibrations, so they requiregreater distance or space of bridge uninterfered With by other notes.

It also consists in electrically isolating the case, sound-board, andall that produces and adds to the tone of the instrument, from the ironframe or plate or mere sustaining portion, whereby whatever electricitymay be generated or attracted by the vibration of the strings is allforced into and prevented from escaping in any way but through thesound-board.

It also consists in making the case of the grand piano-forte narroweracross the middle than at the r ar end and wider than usual at the rearend, the object being to make the case, which I construct ot a mereshell of wood and with a bottom sound-board, of a form approximating tothat of the violin or guitar,-Which is the form best adapted for sound,and to obtain a greater width oi soundboard in the lower or bass part ofthe instrument, where greater vibration is necessary.

It further consists in providing an opening at the left-hand frontcorner of the soundboard of a grand piano-forte, for the purpose ofgiving a better opportunity for the sound to come out from theinstrument when a bottom sound-board is used.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

In carrying out my improvements I construct the piano-forte withastrong, open base frame, A, of wood, the outside of which gives form tothe rim B of the case, which consists of amere shell, and I cover thebottom of the said frame with a thin sound-board, C, according to myLetters Patent No. 19,081. The sound-board proper, D, "or, as lprcfer toterm it, the tone-magnifier,77 is glued to the rim B of the case at itssides and back, and its front end is glued to a timber, D', which restson the base-frame A.

E F G H H are the straight sound-board bridges, Jrive in number, thelast two, H H', being of the same height, but the others being ofgradually-diminishedheights, to permit the arrangement of the strings infour overstrung tiers, the lowest tier, a a', embracing the strings atthe treble end of the scale, resting on thelowest bridge, E, the nexttier, a2 a2, einbracing a number of strings lower in the scale, restingon the next bridge, F, the next tierembracing a number of strings, c3a3, still lower in the scale, resting on the bridge G, and the next tierembracing the lowest or bass strings, a4 a4, resting upon the highestbridges, II H. The reason for using two bridges, I-I Hf, for theuppermost tier of strin gs, d4 di, is to enble the said strings to bebrought wide enough apart without making the bridge of too great length.The bridges F 'G H H are severally arranged over the middle of the widthof the sound-board, where there is the greatest amount of vibration; butthe bridge, E, for the treble strings a' a,is arranged with its lefthand end, where the shortest strings are supported, close to the side ofthe instrument, those strings requiring a very firm bearing. The bridgeE forms a very acute angle with the hammer-line, which is indicated indotted outline and marked s s in Fig. l, the bridge F a less acuteangle, the bridge G a still less acute angle, and the bridges H H',which are parallel, theleast acute angles. The above increase in theangles formed by the straight bridges with the hammer-line enables thenecessary progression of increase of width between the bridge-bearingsand between the strings from the highest to the lowest notes-that is tosay, enables the distance of each string from the next onelower in thescale to be made greater than its distance from the next one higherinthe scale. By this arrangement of bridges the vibration of the board isrendered more free than by any system heretofore used, as they are all,with the exception of E, over the middle of the board; and the straightform interferes less than the curved form ot' bridge.

The strings are sustained independently of the case by means of an ironplate or frame, I, corresponding with the form ofthe case, theyWrest-plank J being bolted to the said plate, and the said plate issupported upon the frame A by means of several iron standards, L L, fromwhich it is electrically isolated by means of glass or other suitablematerial which is a non-conductor ot' electricity. The

isolation represented for each standard (see- Fig. 3) is composed of acylindrical tube or thimble, b, of glass, which is titted into a cavityin the top of the standard, and to a hole in two flat rings, c and d, ofwhich c is iitted to the vexterior of the thimble below the pla-te I,and

d is placed above the thimble b and plate I. A screw, e, passing throughthe ring d and tube or thimble b and screwing into the standard, securesthe plate I to the standard, and at the same time secures the glass inplace. Washers of india-rubber or other soft material may be interposedbetween the glass and the plate I and standard L. For con- Venience ofsecuring the standard L to the frame I, I cast two standards on onebase, L,

as shown in Figs. 2 and 3. At the front of back of the case, inconnection with the thin sides and thin vibrating bottom or additionalsound-board O, gives the instrument more of the character of the violin.

The opening at the left-hand front corner of the sound-board ortonemagniier D is shown atj'fg in Fig. l. Io form this opening, thesound-board is cut off at the abovementioned corner from a point four ortive inches from the first or treble bridge, E, and parallel with thesecond bridge, F. The timber D, which supports the front of the board,is also cut away up to the point g, Where the board commences to beglued onto it. By this means more room is provided for the sound to comeont than has heretofore been provided when the whole of the bottom ofthe instrument has been closed up by a bottom soundboard, C.

I am aware that F. C. Lighte obtained Letters Patent for what he termedinsulators but these insulators are applied between the wrest-plank andthe iron plate and otherwise in a different manner from the means ofelectrical isolation, and for an entirely different purpose, and Ihereby disclaim such isolation.

Vhat I claim as my invention, and desire to secure by Letters Patent,`is

l. The employment throughout the scale of a pianoforte of a system ofstraight bridges, of different heights, whereby the strings are broughtin overstrung ltiers or sections over or as near as possible to themiddle portion of the sound-board, substantially as herein described,and other results, hereinabove mentioncd, are obtained.

2. Electrically isolating the case, the soundboard, and all that isinstrumental in producing or developing the sound from the iron frame ormere sustaining portion of the pianoforte, substantially as and for thepurpose herein specified.

3. Gonstructin g the case of the grand pianoforte of violin form-that isto say, with both sides curved, and with the rear portion wider than themiddle portion, substantially as and for the purpose herein described.

4. In combination with a bottom soundboard, C, in a grand pianoforte,the opening jfg at the front left hand corner ot' the up persound-board, D, substantially as and for the purpose herein speciiied.

. SPENUER B. DRIGGS.

Witnesses:

THos. L. J. DOUGLAS, M. M. LIVINGsToN.

